By the laws of physics, drag is approximately proportional to the square of the speed, so even a slightly faster flight requires a lot more fuel. Hiking a plane's velocity by 10 percent takes 21 percent more energy. Speeding up by 40 percent approximately doubles fuel consumption. Shorter flights can save airlines money on labor, but not enough to offset the loss in efficiency.

According to a 2008 report by the Associated Press, JetBlue saves approximately $13.6 million a year in jet fuel by merely adding an average of just under two minutes to each flight, and Northwest Airlines saves about $600,000 by adding just four minutes solely to its flights to and from Hawaii.

So the next time you’re lamenting your lengthy flight, consider that airlines, like many consumers, are trying to save a buck when it comes to gas.